2 33rd annual Boston Harmony Sweepstakes A Cappella Festival: 8-10:15 p.m. April 1, Somerville Theatre, 55 Davis Square. Now in its third decade, the Harmony Sweepstakes A Cappella Festival will present a lineup of talented singing groups at the Boston Regional event. The Harmony Sweepstakes was the inspiration behind the hit NBC prime time show, “The Sing Off.” This show will feature special guests North Shore Acappella, who not only were contestants on “The Sing Off,” but who are also the Harmony Sweepstakes A Cappella Festival 1991 national champions. Competing this evening are Birdland Avenue, Bosonality, Carpe Singem, Drive, Fermata Town, Fireside Quartet and Harmoniuos Soul. Cost: $25-$35. For information: http://www.harmony-sweepstakes.com/boston.

5 James B. Conroy presents “Lincoln’s White House”: 7 p.m. April 6, Medford Historical Society and Museum, 10 Governors’ Ave. Local, noted Civil War author James Conroy has written the definitive book to date on the life in the Lincoln White House. Using material from those who lived there and visited, from servants to statesmen, at a time of high stakes and high anxiety, Conroy provides an intriguing and dramatic picture of the time and place of Abraham Lincoln. For information: http://www.medfordhistorical.org.